Block copolymers of fiber-forming acrylonitrile polymers and polymeric 2,2-disubstituted propiolactone



United States Patent Olfice 3,538,195 Patented Nov. 3, 1970 Int. Cl.C08f 29/56 US. Cl. 260-898 7 Claims ABSTRACT OF THE DISCLOSURE Thisinvention relates to new polymeric compositions derived fromacrylonitrile which are block copolymers of a fiber-formingacrylonitrile polymer and a polymeric 2, 2-disubstituted propiolactone.Fibers thereof exhibit enhanced recovery and improved modulus when hotand wet.

This application is a division of my copending application, Ser. No.545,545, filed Apr. 27, 1966 now US. Pat. 3,379,794.

This invention relates to new polymeric compositions derived fromacrylonitrile. More specifically, the invention relates to acrylonitrilepolymer compositions from which fibers can be made exhibiting markedlyenhanced physical properties in the hot, wet state. This inventionfurther relates to novel processes of making the novel polymericcompositions derived from acrylonitrile.

Despite wide commercial success of fibers of acrylonitrile polymer, thephysical properties of the fibers are quite poor when they are incontact with hot water, and this deficiency has restricted theirapplication for many uses. For example, the fibers are easily stretchedout of shape when they are subjected to tension in a hot dye bath, ordeformed when processed in the presence of steam, owing to the lowmodulus of the fibers when hot and wet. Fabrics made of the fibers areeasily wrinkled, owing to the low recovery exhibited by the fibers.There has been a strong incentive to improve these properties of thefibers, providing that the improvement could be achieved withoutimpairment of other desirable properties of the fiber, but such a resulthas not been realized from the various chemical and physicalmodifications of the fiber structure which have been tried hitherto.

It has now been found that a polymeric material consisting essentiallyof an acrylonitrile polymer and a polymeric 2,2-disubstit-utedpropiolactone can be formed into fibers exhibiting enhanced recovery andstrikingly improved modulus when hot and wet, compared with conventionalfibers formed in the same manner of unmodified acrylonitrile polymer.The fibers also exhibit good tenacity values, comparable to those ofunmodified conventional fibers. Similarly enhanced recovery and modulusare exhibited by films prepared from the novel composition. The novelpolymeric material is preferably a blend of an acrylonitrile polymer anda polymeric 2,2-disubstituted propiolactone. In another embodiment ofthe novel polymeric material the polyester segment consistingessentially of recurring ester structural units derived from a2,2-disubstituted propiolactone is attached directly to theacrylonitrile polymer molecule. The polyester segments may be grafted asside chains on the acrylonitrile polymer molecule; however, betterproperties are achieved in the copolymeric form of the composition whenthe polyester segment is attached to the end of the acrylonitrilepolymer molecule to form a block copolymer.

More specifically, the novel product of the invention is a fiber-formingpolymeric material consisting essentially of (I) 3 to 25 mol percent ofa polyester component of LlT wherein n is an average number of at least20 and Q and Q are individually selected from the group consisting ofalkyl radicals of 1 to 4 carbons and chlorine-substituted alkyl radicalsof l to 4 carbons, or Q and Q together join to form an alicyclic ring,and

(II) to 97 mol percent of a fiber-forming addition polymer componentselected from the group consisting of acrylonitrile homopolymers andcopolymers of acrylonitrile with other ethylenically unsaturatedmonomers, no less than 75 mol percent of the combined said components(I) and (II) having the formula As used herein, mol percent" values arebased on the repeating structural units.

In a preferred embodiment of the invention, the polyester component andthe acrylonitrile polymer component are separate molecular species andthe composition is a blend of the species. In another embodiment of theinvention, the recurring ester structural units of the polyestercomponent are attached to the molecular chain of the acrylonitrilepolymer component forming a graft polymer. In still another embodiment,the recurring ester structural units of the polyester component areattached to the terminal structural units of the acrylonitrile polymercomponent forming a block polymer. A useful solvent for these productsis hexafluoroisopropanol.

The invention also comprehends a process for making the products of thepresent invention, wherein a solution of the acrylonitrile polymer isformed and a 2,2-disubstituted propiolactone is added to the solutionand polymerized in the presence of the dissolved acrylonitrile polymer.A suitable solvent in which the process may be carried out isdimethylformamide. In one embodiment of the process, the acrylonitrilepolymer has no effective initiator groups and the 2,2-disubstitutedpropiolactone is polymerized by heating the mixture to form separatepolymer molecules blended with the acrylonitrile polymer. If desired, aninitiator may be added to facilitate the polymerization reaction. Inanother embodiment of the process, the acrylonitrile polymer is anegatively charged radical which causes the added 2,2-disubstitutedpropiolactone to commence polymerization as an attachment to theacrylonitrile polymer molecule. The negatively charged radicals may beanionic substituents on the chain, such as sulfonate or carboxylategroups, in which case the resulting product is a graft copolymer. Instill another embodiment of the invention, the acrylonitrile polymer isformed by anionic polymerization and the 2,2-disubstituted propiolactoneis added to the polymerization mixture after the acrylonitrile polymerhas been formed and while the polymer still carries a negative charge ona terminal carbon atom, in which case the resulting product is a blockpolymer.

As used herein, the term acrylonitrile polymer includes both thehomopolymer, polyacrylonitrile, and copolymers thereof derived fromacrylonitrile together with minor amounts of one or more otherunsaturated organic compounds copolymerizable with acrylonitrile. Suchcompounds include acrylate esters such as methyl acrylate, methacrylateesters such as methyl methacrylate, esters of u-chloroacrylic acid suchas methyl a-chloroacrylate, acrylamide, methacrylamide, methyl vinylketone, phenyl vinyl ketone, vinyl acetate, benzoate, and the like. Thedyeability of the polymer can be enhanced by the addition of an anionicmodifier such as sodium or potassium pvinylbenzenesulfonate, preferablyas a terpolymeric component as disclosed and claimed by Millhiser in hisU.S. Pat. 2,837,501.

The 2,2-disubstituted propiolactones which may be employed in accordancewith the present invention consist essentially of those given by theformula:

(Qlll Q-O o=o t... 1.

Typical 2,2 disubstituted propiolactones include 2,2dimethylpropiolactone (pivalolactone) (Q=Q=CH 2,2- diethylpropiolactone(Q=Q=CH CH 2 methyl 2- chloromethylpropiolactone (Q=CH Q"=ClCH 2,2-bis(chloromethyl)propiolactone (Q=Q=ClCH 2 methyl-Z-ethylpropiolactone(Q=CH Q"=CH CH 2, 2-dipropylpropiolactone (Q=Q=CH CH CH2,2-dibutylpropiolactone -(Q=Q=CH CH CH CH and 2,2-pentamethylenepropiolactone Such propiolactones may be usedindividually or in combination to make up to the required percentage ofester structural units in the polymeric material.

The following examples will serve to illustrate the present invention.The following terms and abbreviations are used in the example: Fiberproperties of tenacity, elongation, and initial modulus are reported intheir conventional units of g./den., percent, and g./den., respectively.The terms work recovery and tensile recovery are reported in percent.These terms are used as defined in R. G. Beaman and F. B. Cramer, J.Polymer Sci., Vol. 21, 228 (1956). Work recovery and tensile recoveryvalues in the examples are reported not only for the dry,room-temperature fibers but also for wet fibers at 50 C., correspondingto the typical condition of the fibers during laundering.

The expression inherent viscosity, ninh, as used in the examples, isdefined as In 1ml wherein c is the concentration of the polymer in 100ml. of the solvent and 1 is the symbol for relative viscosity (the ratioof the flow time of the polymer solution relative to the flow time ofthe solvent). The viscosity measurements are made in 0.5% solutions ofthe polymer in dimethylformamide (DMF) at 30 C.

In the following examples parts and percentages are by weight unlessotherwise indicated.

The first series of examples illustrate the preparation of afiber-forming polymer blend consisting essentially of (I) 3 to 25 molpercent of a polyester component of the formula:

lo..- 41001. L i 1.

wherein n is an average number of at least 20 and Q and Q areindividually selected from the group consisting of alkyl radicals of 1to 4 carbons and chlorine-substituted alkyl radicals of 1 to 4 carbons,or Q and Q together join to form an alicyclic ring, and

(II) 75 to 97 mol percent of a fiber-forming addition polymer componentselected from the group consisting of acrylonitrile homopolymers andcopolymers of acrylonitrile with other ethylenically unsaturatedmonomers, no

less than 75 mol percent of the combined said components (I) and (II)having the formula EXAMPLE 1 Preparation of blends of acrylonitrilepolymer with polypivalolactone To 240 g. of dimethylformamide is added60 g. (1.13 mols, based on the weight of the repeating unit) ofpolyacrylonitrile having an inherent viscosity of 1.96. The mixture iswarmed and heated to complete solution of the polymer, after which it isallowed to cool to room temperature. To this solution is added 6.0 g. ofpivalolactone (0.06 mols), following which the mixture is centrifugedfor five minutes to remove bubbles, transferred to a spinning cell,heated to 103 C., and extruded at a pressure of 7.73 kg./cm. p.s.i.)through a spinneret containing 10 orifices, each 0.165 mm. (6.5 mils) indiameter. The total solutes in the spinning solution amount to 21.5%.Nitrogen at a temperature of 200 C. is passed vertically downwardthrough the spinning cell. The yarn is wound up at 137 meters/min. (150ypm.), washed with cold water to extract residual dimethylformamide, anddried in air. The composition of the fibers is determined from analysisfor carbon, hydrogen, and nitrogen: the analysis indicating that thefiber is composed of 96 mol percent polyacrylonitrile and 4 mol percentpolypivalolactone, apparently as a blend resulting from thermalpolymerization of the pivalolactone in the spinning cell.

The fibers are drawn 5.0 X through steam at 0.8433 kg./cm. (12 p.s.i.)gauge and relaxed 10% at 190 C. The fiber denier is 1.8 per filament.The properties of these fibers are shown on Table I.

By contrast, control fibers of unmodified polyacrylonitrile spun in thesame manner and drawn 5.5x at 180 C. are prepared. The properties ofthese fibers are also shown in Table I and are coded as Example l-C.

EXAMPLE 2 Preparation of blends of acrylonitrile polymer withpolypivalolactone Tetrabutylammonium hydroxide (1 ml.) in methanol isneutralized with 0.122 g. of benzoic acid and added to 200 ml. of-butyrolactone. Fifty g. of acrylonitrile polymer is added and dissolvedat C. A solution of 25 g. (21 mol percent) of pivalolactone and 20 ml.of vbutyrolactone is added to the reaction mixture at 110 C. After onehour, the gel is transferred to a spinning cell and spun, after whichthe fibers are drawn 8 at 145 C. and relaxed 14% at 145 C. Theproperties of these fibers are shown in Table 1.

EXAMPLE 3 Preparation of blends of acrylonitrile polymer withpolypivalolactone Tetrabutylammonium hydroxide (1 ml.) in methanol isadded to 225 ml. of N-methylpyrrolidone. Fifty g. of acrylonitrilepolymer is added and dissolved at 76 C. A solution of 10.3 g. (10 molpercent) of pivalolactone in 20 ml. of y-butyrolactone is added to thereaction mixture in the form ofa fine spray. After two hours the gel istransferred to a spinning cell and spun, after which the fibers aredrawn 13.5 at 140 C. The properties of these fibers are shown in TableI.

EXAMPLE 4 Preparation of blends of acrylonitrile polymer withpoly(2,2-diethylpropiolactone) Following the procedure of Example 3, inanother experiment, the pivalolactone is replaced by 21 g. (15 molpercent) of 2,2-diethylpropiolactone. Fibers are spun and drawn 8.0x at135 C. The properties of these fibers are shown in Table I.

EXAMPLE Preparation of blends of acrylonitrile, methyl acrylate andsodium p-vinylbenzenesulfonate polymers with polypivalolactone Theprocedure of Example 1 is repeated, using 70 g. of an acrylonitrilecopolymer having an inherent viscosity of 1.5 and comprising 96 molpercent acrylonitrile, 3.8 mol percent methyl acrylate, and 0.2 molpercent sodium p-vinylbenzene sulfonate dissolved in 200 g. ofdimethylformamide, to which is added 70 g. of pivalolactone. The totalsolutes in the mixture amount to 41%. After the mixture is centrifugedand transferred to the spinning cell, the solution is heated to 110 C.and extruded at a pressure 35.2 kg./cm. (500 p.s.i.) gauge through aspinneret containing orifices, each 0.165 mm. (6.5 mils) in diameter.The nitrogen at the spinning cell has a temperature of 145 C. The yarnis wound up at 91.4 meters/ min. (100 y.p.m.), washed with cold water toextract residual dimethylformamide, and dried in air. The composition ofthe fibers is determined from analysis for carbon, hydrogen, andnitrogen: The analysis indicating that the fiber is composed of 84 molpercent polymerized acrylonitrile, 3.3 mol percent polymerized methylacrylate, 0.2 mol percent polymerized p-vinylbenzenesulfonic acid, and12.5 mol percent polymerized pivalolactone, apparently formed as a blendof the original acrylonitrile copolymer with polypivalolactone resultingfrom the thermal polymerization of the pivalolactone in the spinningcell.

The fibers are drawn 5.0x over a hot plate maintained at 150 C. Thefiber denier is 1.6 per filament. The properties of these fibers areshown in Table I.

By contrast, control fibers of the same acrylonitrile copolymer to whichno pivalolactone is added, spun in the same manner and drawn 5.0xthrough steam at 1.27 kg./cm. (18 p.s.i.) gauge and relaxed 14% at 175C. are prepared. The properties of these fibers are also shown in TableI and are coded as Example 5-C.

In the block copolymer at least one end of the polyester component isattached to the terminal group of the acrylonitrile polymer.

EXAMPLE 6 Preparation of block copolymers of acrylonitrile andpivalolactone A 4-necked, round-bottom flask equipped with a nitrogeninlet, a thermometer, a stirrer, and a drying tube exchangeable With adropping funnel is flamed to ensure that the apparatus is dry. Afterstarting a continuous stream of dry nitrogen gas into the flask, 42.0 g.(0.08 mol) of acrylonitrile and 300 g. of dimethylformamide are added,each previously vacuum distilled from P 0 to ensure dryness. The flaskis cooled to 40 C. by external application of an acetone-Dry Ice bath,after which 1 ml. of a saturated (0.7%) solution of sodium cyanide indimethylformamide is added to the flask through a rubber septum using ahypodermic syringe. The mixture is stirred continuously. The temperaturerises rapidly, but with the aid of the external cooling is not permittedto rise above about 30 C. With continued external cooling, thetemperature drops to about 1020 C. as the solution becomes more viscous,whereupon 20.0 grams (0.2 mol) of pure pivololactone is introduced intothe flask through a dropping funnel. A rapid further increase in theviscosity of the solution is noted. When the viscosity of the solutionappears to reach a constant value, it is centrifuged. The solution,which contains 17.2% solids is then transferred to a dry spinning cell.

The solution is extruded at 135 C. and 45.7 l g./cm. (650 p.s.i.) gaugethrough a spinneret containing ten orifices, each 0.165 mm. 6.5 mils) indiameter, into a stream of nitrogen passed vertically downward at therate of 0.17 cu. meter/min. (6 cu. ft./min.) having a temperature of 175C. at the bottom of the cell and 165 C. at the top of the cell. The yarnis wound up at 91.4 meters/ min. (100 y.p.m.), Washed with cold water toextract residual dimethylformamide, and dried in air. The polymericcomposition of the fibers, theoretically 80 mol percent/2O mol percentpolyacrylonitrile/polypivalolactone, is determined by analysis fornitrogen to have an actual TABLE L-PROPERTIES OF FIBERS OF BLENDEDPOLYMERS Modulus, g.p.cl.,

Work recovery, g.p.d.

Tensile recovery, Tenacity, g.p.d.,

Draw Percent re- 90 C. wet/R31. (3% elongation). g.p.d. (3% elongation),elongation percent Example ratio laxation dry 0. wet/RT. dry 50 C.wet/R/I. dry 1LT. dry) 1 R.T. dry-Room temperature (21 0.), dry sample(in equilibrium with air at 65% relative humidity).

The second series of examples refer to a product in the form of afiber-forming block copolymer consisting essentially of (I) 3 to 25 molpercent of a polyester component of the formula:

value of 77 mol percent/23 mol percent. Samples of the fibers are thendrawn over a 180' C. hot plate at various draw ratios as indicated inTable II, following which they are relaxed at 180-185 C.

The properties of the fibers are listed in Table II, together with theproperties of a control fiber of acrylonitrile polymer containing nopolypivalolactone modifier designated as Example 6-C. Also shown areresults obtained for fibers prepared by changing the proportion ofreagents, using 48.2 g. (0.9 mol) of acrylonitrile and 10.0 g. (0.1 mol)of pivalolactone designated as Example 7. The spinning solution, whichcontains 16.2% solids, is spun at 130 C. and 22.8 kg./cm. (325 p.s.i.)gauge through a spinneret containing 5 orifices, each 0.13 mm. (5 mils)in diameter. The nitrogen is introduced into the cell at a rate of 0.141cubic meter/min. (5 cu. ft./min.)

and a temperature of 175 C. at the bottom of the cell and 155 C. at thetop of the cell. The windup speed is 94.1 meters/min. (103 y.p.m.). Thepolymeric composition of the fibers, nominally mol percent/10 molpercent polyacrylonitrile/polypivalolactone, is determined by analysisfor nitrogen to have an actual value of 84 mol percent/ 16 mol percent.

7 EXAMPLE 8 Preparation of block copolymers of acrylonitrile,pivalolactone, 2,2-diethylpropiolactone The general procedure of Example6 for the preparation of 90 mol percent/ 10 mol percentpolyacrylonitrile/ polypivalolactone is repeated, except that one-fourthof the pivalolactone is replaced by 2,2-diethylpropiolactone to alterthe composition to 90 mol percent/7.5 mol percent/2.5 mol percentpolyacrylonitrile/polypivalolactne/ poly(2,2-diethylpropiolactone). Theresulting block copolymer is spun and the fibers are drawn 6.0 withoutsubsequent relaxation. The properties of these fibers are shown in TableII.

In a similar experiment, another block copolymer is prepared followingthe above procedure, except that threefourths of the pivalolactone isreplaced by 2,2-diethylpropiolactone so that the resulting copolymer hasthe composition 90 mol percent/2.5 mol percent/ 7.5 mol percentpolyacrylonitrile/polypivalolactone/poly(2,2 diethylpropiolactone). Theresulting block copolymer is spun and the fibers are drawn 4.0 at170-175 C. and relaxed 7% at 180 C. The properties of these fibers areshown in Table II and designated as Example 9.

8 EXAMPLE Preparation of graft copolymers of pivalodactone withacrylonitrile, methyl acrylate, and sodium p-vinylbenzenesulfonate Acopolymer comprising 96 mol percent acrylonitrile, 3.8 mol percentmethyl acrylate, and 0.2 mol percent sodium p-vinylbenzenesulfonate,prepared as described by F. R. Millhiser in his US. Pat. 2,837,501, isslurried in dilute hydrochloric acid and then washed with water, afterwhich the copolymer is dried. One hundred and forty (140) ml. ofdimethylformamide is cooled to 40 C., and to this is first added 0.2 ml.of a 1 M tetrabutyl ammonium hydroxide solution in methanol followed by50.0 g. of the dried copolymer. The resulting mixture is allowed to warmto about to C., at which point complete solution occurs. To this isadded a mixture of 17 g. of pivalolactone and ml. of dimethylformamidethrough a syringe, while the polymer solution is vigorously stirred.Polymerization of the lactone commences. After 5 minutes, the solutionis centrifuged and transferred to the spinning cell. The solutioncontains 25% solids.

The solution is extruded at 8587 C. and a pressure TABLE II.-PROPERTIESOF FIBERS OF BLOCK OOPOLYMERS Modulus, g.p.d.,

Work recovery. g.p.d

Tensile recovery, Tenacity, g.p.d.,

Draw Percent re- 90 C. wet/RT. (3% elongation), 50 g.p.d. (3%elongation), elongation percent Example ratio laxation dry 1 C. wet/R.T.dry 50 C. wet/RT. dry (R.T. dry) 1 R.I. dryRoom temperature (21 0.), drysample (in equilibrium with air at relative humidity).

In another experiment, polyacrylonitrile/polypivalolactone blockcopolymer having a theoretical mol percent/ 20 mol percent compositionis prepared. After the reaction mixture has been stirred for threehours, a film is cast. By analysis for nitrogen the actual compositionof the block copolymer is 78 mol percent/ 22 mol percentpolyacrylonitrile/polypivalolactone. Strips of film 50 mm. x 1.6 mm. (2"x V are cut and drawn 6 over a 160 C. hot plate. The average drawndenier is 15. The drawn film is tough and flexible. It has a modulus of19 g.p.d. at C. when wet, while the dry film at room temperature has amodulus of 64 g.p.d. The tenacity and elongation of the dry film are 3.0g.p.d. and 9% respectively.

In the third series of examples the product formed is a fiber-forminggraft polymer consisting essentially of (I) 3 to 25 mol percent of apolyester component of wherein n is an average number of at least 20 andQ and Q are individually selected from the group consisting of alkylradicals of 1 to 4 carbons and chlorine-substituted alkyl radicals of 1to 4 carbons, or Q and Q together join to form an alicyclic ring, and

(II) 75 to 97 mol percent of a fiber-forming addition polymer componentof copolymers of acrylonitrile with other ethylenically unsaturatedmonomers, no less than 75 mol percent of the combined said components(I) and (II) having the formula and wherein at least one of saidmonomers when polymerized is a trivalent structural unit being connectedby two valences within the polymeric chain of said component II and bythe third valence to said component (1).

ranging from 4272 kg./cm. (600-1050 p.s.i.) gauge through a spinneretcontaining 10 orifices, each 0.13 mm. (5 mils) in diameter, into astream of nitrogen having a temperature of about 186 C. passedvertically downward in the spinning cell. The yarn is wound up at 68meters/min. (74 y.p.n1.), washed with cold water to extract residualdimethylformamide, and dried in air. The composition of the fibers is17.9 mol percent polymerized pivalolactone, 78.8 mol percent polymerizedacrylonitrile, 3.1 mol percent polymerized methyl acrylate, and 0.2 molpercent polymerized p-vinylbenzenesulfonic acid. The fibers are thendrawn, in two stages, 2X in water at 72 C. and 3X over a hot plate at170 C. The properties of these fibers are shown in Table III.

A control fiber composed of a copolymer of 96 mol percent acrylonitrile,3.8% methylacrylate, and 0.2 mol percent sodium p-vinylbenzenesulfonatedrawn 5.0x through steam at 1.27 kg./cm. (18.2 p.s.i.) gauge is alsoshown in Table III and is designated as Example 10-C.

EXAMPLE 11 Preparation of graft copolymers of pivalolactone withacrylonitrile/acrylic acid polymer Two liters of water is degassed withnitrogen and heated at 50 C. Two hundred g. of acrylonitrile and 2.7 g.of acrylic acid (100:1 molar ratio) are added, and the pH of thesolution is adjusted to the range of 33.5 using 1.0 N sulfuric acid. Tothis mixture are quickly added, in the order named, previously preparedquantities of 5 mg. of ferrous ammonium sulfate hexahydrate, 0.5 g. ofpotassium persulfate in 100 ml. of water and 2.5 g. of sodiummetabisulfite in 250 ml. of water. The reaction mixture, which becomescloudy within a short time, is stirred quite slowly for one hour. Thepolymer is filtered off, washed with water, washed with acetone, anddried in a vacuum oven.

Fifty g. of acrylonitrile/acrylic acid copolymer, prepared as describedabove, is mixed with 225 ml. of dimethylformamide at room temperature.The mixture is stirred vigorously to dissolve the copolymer and then, asstirring is continued, 12.9 g. (12 mol percent) of pivalolactone in 20ml. of 'y-butyrolactone is added dropwise over a period of time. Themixture is transferred to a spinning cell and heated at 86 C. for twohours to permit completion of polymerization, following which theresulting gel is spun at 100 C. The fibers are drawn at 150 C. x andthen relaxed 14% at 150 C. The properties of these fibers are shown inTable III.

In a similar experiment using an acrylonitrile/acrylic acid copolymer)(mol ratio 1000/1) the amount of pivalolactone added is reduced to 4.4g. (4 mol percent), and the fibers spun from the copolymer are drawn 4at 155 C. and relaxed at 175 C. The properties of these fibers are shownin Table III designated as Example 12.

EXAMPLE 12 Preparation of graft copolymers of 2,2-diethylpropiolactonewith acrylonitrile/acrylic acid polymer The experiment as shown inExample 11 is repeated again, employing 186 ml. of dimethylformamide assolvent, 38.8 of acrylonitrile/acrylic acid copolymer (mol ratio 100/ 1)and 12.8 g. of 2,2-diethylpropiolactone (12 mol percent) in place of thepivalolactone. Fibers are spun from the resulting graft copolymer, andthe spun fibers are drawn 5 X at 175 C. and relaxed 14% at 180 C. Theproperties of these fibers are shown in Table III.

10 What is claimed is: 1. A fiber-forming polymeric material consistingessentially of a block copolymer of (I) 3 to 25 mol percent of apolyester component of the formula:

wherein n is an average number of at least 20 and Q and Q areindividually selected from the group consisting of alkyl radicals of 1to 4 carbons and chlorine-substituted alkyl radicals of 1 t0 4 carbons,or Q and Q together join to form an alicyclic ring, and (II) 75 to 97mol percent of a fiber-forming addition polymer component selected. fromthe group consisting of acrylonitrile homopolymers and copolymers ofacrylonitrile with at least one other ethylenically unsaturated monomer,no less than 75 mol percent of the combined said components (I) and (II)having the formula -OH2OH- 2. The polymeric material of claim 1 whereinsaid component (I) is polymerized 2,Z-dimethylpropiolactone. 3. Thepolymeric material of claim 1 wherein said component (I) is polymerized2,Z-diethylpropiolactone.

4. The polymeric material of claim 1 wherein said com- IABLEIIL-PROIERTIES OF FIBERS OF GRAFI COPOLYMERS Modulus, g.p.d.,

Work recovery, g.p.d.

Tensile recovery, Tenacity, g.p.d.,

Draw Percent re- 90 C. wet/RIP. (3% elongation), g.p.d. (3% elongation),elongation percent Example ratio laxation dry 1 C. wet/RT. dry 50 C.wet/RT. dry (RIP. dry) 1 RIP. dry-Room temperature (21 0.), dry sample(in equilibrium with air at relative humidity).

The amount of the trivalent structural unit required for producing agraft polymer may be very small in some circumstances. It appears thatthe minimum concentration of these trivalent linking units is equal tol/n of the mol percent of the polyester component (wherein n is aspreviously defined).

As is seen from Tables I, II, and III, fibers of the polymeric materialsof the present invention have a greatly improved modulus at hot-wetconditions when compared with the corresponding acrylonitrile polymerfibers not containing polymerized 2,2-disubstit-uted propiolactone.These unexpectedly higher modulus values of the fibers under hot-wetconditions are important because fibers and fabrics are frequentlyprocessed under these conditions. Significantly this improvement isobtained without undesirable efiect on the other important fiberproperties listed, i.e., work recovery, tensile recovery tenacity, andelongation. Because of this improved property, the fibers of thepolymeric materials of the present invention are highly useful in thetypical ap plications of textile fibers. Utility is also present inimproved films formed of these polymeric materials.

The polymeric material of the present invention can contain conventionaladditives such as stabilizers, antioxidants, delusterants, pigments,dyes, antistatic agents, and the like. Other aspects of this inventionwill be obvious to those skilled in the art.

It is to be understood that the foregoing description is by way ofexample only and that various modifications and changes in the detailsmay be made without departing from the spirit of the invention and thescope of the following claims.

ponent (I) is polymerized 2,2-dimethylpropiolactone and2,2-diethylpropiolactone.

5. The polymeric material of claim 1 wherein said component (II) isacrylonitrile homopolymer.

6. The polymeric material of claim 1 wherein said component (II) is thecopolymer of acrylonitrile and methyl acrylate.

7. The process of forming the block polymer of claim 1, comprising:

(1) forming said component (II) having a negative charge on a terminalcarbon atom by anionic polymerization,

(2) dissolving said component (II) in a suitable solvent,

(3) adding the 2,2-disubstituted propiolactone, which can be polymerizedto form the desired said component (I), to the solution of component(II), and

(4) polymerizing said 2,2-disubstituted propiolactone to form saidcomponent (I) existing as a block polymer with said component (II)References Cited UNITED STATES PATENTS 3,379,794 4/1968 King et al.3,418,393 12/1968 King.

MURRAY TILLMAN, Primary Examiner C. I. SECCURO, Assistant Examiner US.Cl. XJR. 260874 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 538,l95 Dated November 5, 1970 Inventor) Charles King andFredericl Theodore Wallenberger It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycoi'rected as shown below:

Column 10, line 2 Claim 1,

- CH 4 CH should read GHQ-CH- CH CN Signed and sealed this 29th day ofJune 1971.

(SEAL) Attest: I

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patel ts

